Acoustic duct



FIG. 1 is a front, right side and top perspective view of an acousticduct showing our new design;

FIG. 2 is a rear, left side and top perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines shown represent unclaimed subject matter and form nopart of the claimed design.

CLAIM The ornamental design for an acoustic duct, as shown anddescribed.